Read Fossil meeting 25-27 may ODS.pptx text version

Qualification of New, Commercial Oxide Dispersion Strengthened (ODS) Alloys

24th Annual Conference on Fossil Energy Materials May 25-27, 2010 Sebastien Dryepondt, Oak Ridge National Laboratory, TN Vito Cedro III, National Energy Technology Laboratory, PA Bimal Kad, University of California ­ San Diego, CA Andi Jones, University of Liverpool, UK Bohumil Kazimierzak, Dour Metal, Sro., Slovekia

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Managed by UT-Battelle for the U.S. Department of Energy

ODS Alloys for Fossil Energy Application

-! Increase efficiencies of fossil fuel systems require materials that can reliably operate at higher temperatures and pressures -! ODS steels out perform Ni-based superalloys in terms of creep and oxidation resistance at temperature above 900ºC and could be used up to 1200ºC -! Need to take advantage of the full potential of ODS alloys to balance the cost of alloy fabrication -! Potential applications: HT heat exchanger, fuel nozzles & combustors can for turbines fired with H2

ODS Alloys Process

-!Mechanically Alloyed powder: metallic powder with 5-10 nm Y2O3 particles: nano-precipitates stable at high TºC -!Alloys composition:

ODM751 MA956 MA956HT PM2000 Fe bal. bal. bal. bal. Cr 16.5 20 21.6 20 Al 4.5 4.5 5.9 5 Ti 0.6 0.5 0.4 0.5 Y2O3 0.5 0.5 1 0.5 Other

1.5 Mo 0.5 Ni max

-! Extrusion process to form tubes, bars and sheets: -! Re-crystallization annealing at very high TºC (up to 1380ºC) to suppress grain boundaries

ODS Alloys Microstructure

* *

extrusion direction

*

Longitudinal

Transverse

- Elongated grains - nano Y2O3 precipitates

*Capdevila & Al., Mat. Sci. and Eng. A, 490, 277 (2008)

ODS-Alloys Out Perform Ni-based Superalloys at High Temperature

Excellent Creep resistance of ODS Steels at 1100ºC

80 70 60

ODM751

Stress (MPa)

50 40 30 20 10 0 1 10 100

PM2000 Alloy 230 1038ºC MA 956

Uniaxial creep testing 1100ºC

1000 10000

Duration (Hr)

Lower hoop creep strength resistance

80 70 60

ODM751

Stress (MPa)

50 40 30 20 10 0 1 10 100

PM2000 MA 956 PM2000: flatten tube trans. MA956: flatten tube trans.

1000 10000

Duration (Hr)

Existence of a stress to rupture threshold for a given TºC

80 70 60

ODM751 1100ºC ODM751 1150ºC ODM751 1200ºC PM2000 1100ºC

Stress (MPa)

50 40 30

MA 956 1100ºC

Design20 potential components according to the maximum of allowable stress for any given TºC 10 Use of incrementally-loaded creep testing to estimate that max ! 0

1 10 100 1000 10000

Duration (Hr)

3 oxidation stages have been s of these alloys, in terms of total mass change (total oxygen consumed), have a identified during cyclic exposure

indicated in Fig. 9. For the purposes of modeling, the oxidation behavior has been

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Total Mass Change, mg/cm 2

MA956H 1300°C 'Breakaway' (end of life)

sible simply to equate the oxidation lifetime to the rate of consumption of the e oxide scale(12), so that: tion-limited lifetime = (Al available for oxidation) / (oxidation rate)

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Parabolic oxidation 10 'stage 2' Linear oxidation 'stage 3'

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Transition point Stage 2-3 (! , in µm)

2-3

-1) short transient stage -2) parabolic stage: dominated by oxide scale growth -3) linear stage: scale growth + spallation

0

0

200

400 600 800 1000 1200 1400 1600 Time (hr, in 100 hr cycles)

re 9. Typical form of the oxidation kinetics of ferritic ODS alloys three stages, defined as:

Development of lifetime models based on oxidation rate

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Data for MA956 1000°C

1100°C

10

4

1200°C 1250°C 1300°C

1000

Main Parameters: - All the constant from the parabolic and linear oxidation stages -V: Volume of alloy being oxidized -A: Area exposed to environment -Cb0: Initial mass fraction of Al -Cbb: Mass fraction of Al at which Al2O3 can no longer form

Oxidation-Limited Lifetime, hr

Dashed Lines: predicted lives (2-stage model) Data Points: Observed Lifetimes

100 0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

(specimen thickness) Comparison of predicted and observedbetween experimental data Good agreement oxidation lifetimes for alloy MA956

V/A, mm

and models

basis, and using values of CBb measured at only two temperatures, the model was omparative lifetimes as a function of temperature and section thickness for all of the t. Predictions for 1100°C are shown in Fig. 13, which indicates that all of the alloys xpected to exhibit reasonably similar lifetimes for the thicker sections (V/A > 0.4),

pt MA956) are expected to exhibit reasonably similar lifetimes for the thicker sections (V/A > there is some differentiation among the alloys for thinner sections. Note also that in Fig. 12 the creasing divergence between the predicted and the observed lifetimes as the value of V/A decr 0.5 to 0.2. Presumably, there is some feature of thinner sections that is not treated correctly b Quite similar lifetime for many l.

ODS alloys

PM2000

5 10

4

ODS-Fe Al

3

Oxidation-Limited Lifetime, hr

Oxidation Lifetime, h

3 104

Kanthal APM

ODM751

104 8000 6000 0.2

MA956H

MA956

Data for 1100°C/2012°F

0.4 0.6 0.8 1

V/A, mm

e 13. Comparison of predicted oxidation lifetimes for all the ODS alloys of interest at 1100°C (note that the vertical line denotes the V/A value for a tube of 2.5 mm thickness)

difference in oxidation rate, hence oxidation-limited lifetime, between alloys MA956 and 956 dered surprising since the only major difference in the nominal compositions of these alloys is

Development of Non-Fusion Joining Techniques for ODS Alloys

1. Inertia Welding ­ readily available industrial technique, produces robust joints with acceptable high temperature creep performance. 2. Pulse Plasma Assisted Diffusion produced joints with performance 75% of the base material in incremental load tests 3. Friction stir welding 4. Transient Liquid Phase ­ failure to propagate recrystallization limits application scope 5. Magnetic Pulse joining successful in providing hermetical seals and Joints. Technique applicable only to thin sections. Limited Scope 6. Explosive bonding

SUMMARY OF PRIOR WORK ON JOINING OF OXIDE DISPERSIONSTRENGTHENED ALLOYS, Wright and Al. ORNL/TM-2009/138

Pulsed plasma-assisted diffusion bonding gives excellent results

Failed at 77.3 MPa

·!Miniature specimens/butt joints ·!Joint strength highly-dependent in microstructure ·!Best: >81% of load to fail monolithic

ODS Program FY 2010 Milestones Evaluation of New ODM751R Alloy

·! Obtain sample lengths of ODM 751R extruded rods and tubing for initial structure and properties characterization ·! Perform and report on initial characterization work on ODM 751 samples ·! Status ­! Dour Metal Sro recently established by a former employee of Dour Metals, Belgium to produce ODS alloys ­! ORNL has contracted Dour to produce sample quantities of ODM 751R rod and tube for material characterization studies ­! Samples of mechanically alloyed ODM751R powder have been obtained by ORNL and initial characterization work started.

Superior creep properties for the ODM 751 alloy

80 70 60

ODM751 1100ºC ODM751 1150ºC ODM751 1200ºC PM2000 MA 956

Stress (MPa)

50 40 30 20 10 0 1

Uniaxial creep testing 1100ºC

10 100 1000 10000

Duration (Hr)

ODS Alloy Tube testing up to creep failure

80 70 60

ODM751 1100ºC ODM751 1150ºC MA956 1100ºC ODM751 1100ºC ODM751 1150ºC MA956 1100ºC

0.1 1 10 100 1000 10000 100000

Stress (MPa)

50 40 30 20 10 0

P: Pressure !": hoop stress

"#

2 P $ Ri2 & R0 ) = 1+ 2 + 2 2 ( ( R0 % Ri ) ' Ri *

Duration (Hr)

!

Better Hoop Creep Strength due to overlapping circumferential grains

"onion skin grain shape" British Gas High TºC Heat Exchanger made of ODM751 (36 tubes 3.6m) up to 1150ºC, 3.5 Bar

New ODM 751R alloy

-!ODM751R mechanically alloyed powder has been produced -!by Dour metal and characterized by TEM at ORNL

5-10 nm particles

-!1kg of powder was sent at ORNL for extrusion -!Extrusion parameters will be discussed next week at ORNL

2010 other milestone: ODS alloy awareness workshop

A technical and engineering information exchange workshop between potential users, previous and current suppliers, and Main Goals: R&D leaders alloys

- to promote commercial and user interest in ODS within the fossil energy arena

- to identify barriers for future use and propose solution path - to identify common goals with the nuclear industry and initiate collaborations: production, joining, characterization...

2009/10 subtask: to produce ODS alloy without mechanical alloying

-! to determine the reactive gas atomization processing parameters to approximate MA957 / ODM751R microstructure -! to tailor the cost/properties ratio according to the potential application (ex: Kanthal APMT)

80 70 60

ODM751 PM2000 MA 956 APMT

M. Rhule, proceedings 1991 Heat resistant materials conference

Stress (MPa)

50 40 30 20 10 0 1

1100ºC

10 100 1000 10000

Duration (Hr)

Improvement of oxidation-based lifetime models: effect of H20

) ( '

0.5 mm

0.65 mm

0.75 mm

0.88 mm

01//'2134'5#26,#78

& % $ # " ! !

1200ºC MA 956

0.93 mm

O2+10% H2O O2

7 specimens with different thicknesses

#!! %!! '!! )!! "!!!

!"#$%&'()'*+',-,.%/

-! Decrease of the lifetime due to the presence of H2O

Improvement of oxidation-based lifetime models: effect of CO2 & H20

air

10 µm

50%H2O-50%CO2 2kh 1100ºC = rougher scale with CO2

New environmental rig to test the effect of mixture gas

Creep baseline for PM2000 and "old" ODM751

80 70 60

ODM 751

Stress (MPa)

50 40 30 20 10 0 1

New tests PM2000

PM2000 MA 956

On going

10

100

1000

10000

Duration (Hr)

Effect of annealing/oxidation on the creep resistance

PM2000 dog bone creep specimens pre-oxidized in air 3 different thicknesses, 2 TºC: 1100ºC and 1250ºC

7300h, 1300ºC large formation of porosity 24.5 mm long specimen 1000 hr 1250ºC

On Going/Potential Research relative to ODS alloys

Improvement of ODS alloys hoop creep strength: - change in fabrication process - flow forming process to change grains orientation Improvement of ODS joining techniques - work on welding parameters - post welding process such as flow forming Upgrade of testing equipment - tube pressurization

Conclusion

- ODS FeCrAl alloys have demonstrated unique properties at temperature up to 1200ºC - ODM751R powder will soon be extruded for extensive alloy characterization - Collaboration with potential users, suppliers, technical experts and researchers will be intensified to widen ODS alloys use - On-going research to improve ODS properties, weldability...will evolve to respond to potential users need

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